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York YK Impeller Eye and Balance piston wear.

First off please allow me to preface this post with the fact that I have done dozens of YK repairs with both R-22 as well as the R-134 versions.
Many of these repairs were in the warranty period and some with less than one month run time. I no longer work for the "Big Blue" conglomerate and feel that the response I was given years ago to the problem that I should, "Keep my mouth shut" no longer frightens me...Here goes guys...

As you should be aware, all the YK's(YT's) rotate the impeller Counter-Clockwise facing the Impeller inlet.
"ANY" YK compressor you take apart "Will" have impeller damage with the majority of the wear from impeller grooving from "Both" the Eye seal and Balance piston at the 10-11 O-clock position..The ones with VSD's do show as much damage as the units with DOL or Wye-Delta start.I am certain that others has seen this but have possibly overlooked the source of the problem.
Relax and just visualize what can possibly "Push" the impeller towards the 10 O'clock position....It ain't gonna' happen now is it...Therefore the spring loaded Impeller eye seal (Forget the balance piston now) "MUST" be coming down towards the 5 O'clock position to cut such grooves in this pretty wheel. The Impeller labyrinth has very deep grooves cut into it and can store a certain quantity of oil-refrigerant mixture in these grooves...As the compressor is started this area takes a sudden and and deep pressure drop to the point that the oil-refrigerant mixture "Cannot" exist in this liquid state and as the refrigerant now Expands to almost 1000 times it's area forcing the oil to seal further expansion and literally drives the Labyrinth into the impeller at the 10 O'clock position. The more starts, the deeper the impeller is grooved, the more oily mixture, the better the seal, the greater the force applied on the next start to only deepen the "Grooving" of the once pristeen impeller.

The solution....Simple enough to one who has seen the internals of waaaay' to many Carrier centrifigals. and that is to simply drill a very small hole (1/16th or smaller) on the labyrith seal thru the grooves at the 6 O'clock position. This "Will" allow the oil-ref mixture to drain from the seal eliminating the pushing of the seal and balance piston into such a lovely impeller.
I took it on myself to this on a few compressors before I left the "Big-Blue" fiasco and will be curious as to what the guy who takes them apart someday will think when he sees the lil' hole....I am absolutely certain tho' that unless he has major bearing wear he will NOT see Impeller Grooving...
I only hope that this post is recieved in the intent that it was posted...

Hi Richard,
Some B.P Seal photos that can proove your viewpoint,
these photos I took from the compressor that I asked for your help by mail months ago,
I did drill a 1/16" hole on the center of the ring, hope I can have chance to check it again.

I'm sorry I was not clear in what I think is a solution to a problem that has plagued the Yorks for years. What I have done is to drill all the way thru the grooves (1/16") at the 6 O'clock position with the hole just touching the bottom of the grooved area thereby allowing any mixture of oil/ref. to drain during shutdown.
There is "NO" way that a hole that small, away from the labyrinth sealing area could detract from the sealing effect provided by the seal/balance piston.
I want to thank one and all for not flaming my post, as I truly expected to be assailed by one and all for my attempt at helping others with my view on this...
Taicool....You are one brave soul my friend, to even attempt making such modifications on the word of this lowly scribe...But.....If the seal(s) you modified ever wear "Without" a major bearing failure.....I will chip in on the cost of repairs...Great to hear from you again Tai....
Just wait until I post my findings on the York "J" and "Z" compressor wipeouts...

Richard,
I am not the brave one,
before I did that, I have conveyed the information to a master in the refrigeration field in my country,
in his 30 years career he has a lot of experience on repairing York centrifugal compressors, he totally acknowledge your view.

Taicool;
I am deeply humbled that you as well as the master you referred to would consider the opinions of a one time service man.
I am now retired with my local union(LU72) and am presently working as a maintenance man at a local data center working on lawn sprinklers, changing filters ect. As I absolutely refused to buy into the Johnson Controls Next-Gen methodology of doing service and repairs I chose to leave before I was asked to. I deeply envy and respect those guys behind the windshields of thier service trucks, regardless of company, catching service calls and actually fixing things. In other words...I truly miss the hunt...I guess I am too old to pull the chains any longer and I never learned how to push one. The high point of my day now is this web-site as I look forward to reading the verbal sparring of the likes of Jayguy, Dallas Duster and others. I fear entering the battle of wits these guys use....for I have no weapon in such a fight...

Ok, here it goes i lost sleep over this. I have to ask why is that liquid and oil getting to that high area in machine. I dont recall seeing much oil in any eye seal. also expansion would take the path of least resistance therefore wouldnt gas go all the way around grove and center seal before pushing seal in any direction. I dont see how pressure drop could happen fast enough to cause this (mini explosion). Dont get me wrong i do follow your logic but i have to reason it all out i my head.